Digital electronic devices such as mobile computers and cellular phones are now widely used. Digital terrestrial broadcasting will start in near future. Receivers for the digital terrestrial broadcasting are digital electronic devices such as a liquid crystal display (LCD) and plasma display. Such digital electronic devices include many LSI's therein.
Power circuits of such digital electronic devices include capacitors for bypassing. A multilayer ceramic capacitor, which includes a dielectric ceramic having a high relative dielectric constant, is used when a high capacitance is required in the circuit. On the other hand, a temperature compensating multilayer ceramic capacitor, which includes a dielectric ceramic having a stable temperature characteristic of capacitance, is used when a temperature characteristic of capacitance is important in the circuit.
When a multilayer ceramic capacitor having a high dielectric constant includes the dielectric layer which has a ferroelectric property, the rate of change in temperature of the relative dielectric constant is high and the hysteresis in electric-field versus dielectric polarization characteristic is high. Consequently, noise sound tends to be easily generated on a power supply circuit due to an electrically induced strain.
In contrast, when a multilayer ceramic capacitor is a temperature-compensating type capacitor, the dielectric layer has a paraelectric property. Therefore, the hysteresis in electric-field versus dielectric polarization characteristic is small. The resulting advantage is that this capacitor is free from the electrically induced strain inherent to the ferroelectric property. However, since the dielectric ceramic has a low relative dielectric constant, its accumulating capability is low to cause degradation of its performances as a bypass capacitor.
Therefore, there was a demand for a dielectric ceramic that has a high relative dielectric constant and a stable temperature characteristic in relative dielectric constant.